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R. O. LORENZ. APPARATUS FOR PRODUCING ZING AND LEAD BY ELEGTEOLYSIS. No. 559,729. Patented May 5, 1296.

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(No Model.) 3 Sheets-Sheet 2 R. O. LORENZ. APPARATUS FOR PRODUCING ZING AND LEAD BY ELBGTROLYSIS. No; 559,729. I Patented May 5, 1896.

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' R. 0. LORENZ. APPARATUS FOR PRODUGING ZINC AND LEAD BY BLEGTROLYSIS. No 559,729; Patented May 5, 1896.

fizw rw j" 1 /022 07? MlDREW I RAMMJNOTUUYHIWISMNGTUEQCl UNITED STATES PATENT @rrrcn RICHARD OTTOKA R LORENZ OF GGTTINGEN, GERMANY.

APPARATUS'FOR PRODUCING ZINC AND LEAD BY ELECTROLYSlS.

SPfiClFlIfi-ATTON forming part of Letters Patent No. 559,729, dated May 5, 1896.

Application filed January 4, 1895. Serial No. 533,849. No model.)

To all whom, it may concern.-

Beitknown that I, Brennan OTTOKAR L0- BENZ, a subject of the Grand Duke of SaxolVeimar-Eisenach, and a resident of Gettingen, German Empire, am in possession of an invention for an Apparatus for the Production of Zinc and Lead by Electrolysis of the Melted Chlorids; and I do hereby declare the nature of the said invention and in what manner the same is to be performed to be particularly described and ascertained in and by the following statement thereof-that is to say:

This invention has for its object to effect a rational working of ores containing zinc and lead, in particular of so-called mixed ores, of residue alloys containing zinc and lead and the like. This is effected by converting the compounds containing zinc and lead into chlorids, which are subjected to an electrolytic process under the influence of heat. The production of the chlorids is effected according to the usual methods, the use of which will of course depend upon the nature of the raw materials treated.

\Vhen treating zinc ores, lead ores, and mixed zinc and lead ores, they are roasted in the usual manner for conversion into oxids. If the ores are mainly zinc ores, and consequently contain but little lead, and possibly a small quantity of silver, cadmium, 6120., they are lixiviated directly with hydrochloric acid of medium strength. The lyes then contain mostly zinc chlorid, as also small quantities of chlorids of lead, silver, cadmium, &c., together with. the calcium and magnesium chlorids that may be present. If an excess .of hydrochloric acid has been used, the lye will of course also contain iron and aluminium chloride. As these latter would interfere with the electrolytic action they are precipitated by the addition of roasted ore or zinc residues. The lyes thus purified after having been clarified are evaporated to dryness and melted. If, on the other hand, the ores are mainly lead ores, either pure or containing zinc, and consequently contain so much lead that on liniviating them by means of hydrochloric acid insoluble lead chlorid would be precipitated, the roasted material is lixiviated with dilute acetic acid, and hydrochloric-acid gas is led through the acetate solution, or concentrated acid is added thereto until the whole of the lead and silver are precipitated as chlorids. The clarified lyes are then decanted and heated for the separation of iron and alumina, and then again clarified and decanted. The discharged lyes, which again contain much free acetic acid, are used for the lixiviation of fresh quantities of roasted ore, and this proc ess is repeated until all the acetic acid has combined with zinc. For regenerating the acetic acid the zinc is made to combine with hydrochloric-acid gas introduced for that purpose, andthe lye is then distilled to dryness. The distillate, condensed in the usual manner, now contains the whole of the acetic acid, which can be used again for lixiviatin g fresh quantities of roasted ore.

It is evident that by a suitable mixture of the ores either before roasting or after roastingthe one or the other process of liniviation can be employed, according as circumstances may require.

When treating alloys or waste containing zinc and lead-such as zinc-dust, zinc residues, mufile residues, d7c.-the raw material is treated by the one or the other of the above described processes, according to the composition thereof.

hen zinc chlorid is treated, such as is obtained as lay-product in various technical processes, such as in color-manufactories, it can be at once melted and subjected to electrolysis.

For carrying out the electrolytic process the apparatus shown diagrammatically on the accompanying drawings illustrates my invention.

Figure 1 shows a sectional View of the apparatus. Fig. 2 shows the arrangement of the electrodes; Fig. 3, a plan view of the cover and of the electrodes, in which the conn ectingplate for the electrodes is removed. Fig. 4 is a Vertical section of a retort for recovering muriatic acid from the chlorin.

In the inclined brickwork firing-chamber A is contained a vessel B for containing the melted electrolyte. hen constructed on a small scale, this vessel may be made of porcelain or of refractory clay containing alargc percentage of kaolin and as free as possible from iron. When constructed on a large IOO scale, it is built of enameled bricks, which are bound together by a suitable binding material consisting mainly of kaolin.

The vessel B, of whatever material, is inclosed in an iron casing b for preventing the penetration of com b ustion-gases into the electrolyte. For protecting the casin g Z) against the action of the combustion-gases it can be provided externally with a coating of clay and the like, as more clearly shown at b in Fig. 1.

The vessel A is closed at top by means of a cover C of clay. For carrying off the gases formed by the electrolytic action a lateral tubular branch D is provided, by means of which the gases are led into the earthenware pipe E, in which they are conducted to wherever required. At the lower end the vessel A is tapered to form a pocket G, terminating in a pipe F, the end of which terminates in a dischargin g device I'I.

The section of the vessel B can be of any shape, but would preferably be made circular or elliptic. In the accompanying drawings anelliptic section has been chosen, as seen in Fig. 3. The electrodes are fixed in the cover C, all chinks beinghermetically sealed. The electrodes at their upper ends are united by a plate P, formed of any suitable fireproof material-such as fireproof clay, for example. If the aforesaid chlorids are subjected to electrolysis in an impure statefor' instance, in case they should still'contain a certain quantity of water or of organic substancessucl 1 impurities will also be decomposed by the action of the current. In that case, besides the products resulting from the decomposition of the chlorids,other bodies, and especially gases, will be generated atboth electrodes. If these gases be permitted to intermingle'in statu'nascendi, it can easily happen that they reunite in consequence of their natural atlinity and the high temperature of the' electrolyte." Such.

reunion n'ot'only causes explosions Within'the electrolyte, and in'consequen'ce violent foaming, which much disturbs the regular process, but also a not inconsiderable loss of'energy, because the bodies formed by the reunion of these prod uets2'. e.,'principally hyd roehloric acid and waterare thus subjected to electrolytic decomposition over and over again. Thi's'difficulty' is mainly overcome by the inclined position of the retort containing the electrolyte and by the peculiar shape of the electrodes. The anode is placed above the middle of the retort and the cathode below. Moreover both electrodes are so formed that the gas generated at the bottom side of the anode can freely pass through or around to the upper side and that the metal precipitated at the cathode can' freely sink through or around the electrode .to the bottom of the vessel.

A This purpose'is achieved by forming the electrodes of intersecting parts having numerous openings between the intersections,

. erate temperature.

so that in appearance they resemble network or grates, as shown in Figs. 1 and 2.

In the accompanying drawings, Fig. 3 shows the electrodes composed each of three carbon. bars K K K and L L L of circular section. By these means-i. e., the inclined position of the retort and the grate-shaped electrodes sufficient separation of the products of decomposition is arrived at, although the electrodes present a'consi'derable surface to each other and the distance between them is comparatively small.

' The carbons K K K serve as anodes and L IJ'L as cathodes.

Through the branch D can be introduced a porcelain tube M, serving to charge the vesselA with the melted electrolyte. The gases (chlorin) developed at the anodes rise up along the same, in consequence of the inclined position thereof, in the space R between the anodes and the sides of the vessel and pass through branch D into the pipe E, which leads them to wherever required.

At the cathodes L L L the metal is separated in a molten condition and drips in melted balls into the pocket G, where it is collected and discharged from time to time.

The molten mass subjected to electrolysis always consists of a mixture of lead chlorid and ZlllC chlorid, with or without addition of the other chlorids above mentioned, of which silver chlorid is of particular importance. According to its origin the zinc or the lead canpre'dominate in the mass.

By means of the above-described process of lixiviation by aceti c'acid itis', no doubt, possible to separate the chlorids .of zinc and lead from each other, so that the chlorids of each of the metals" could be separately electrolyzed; but in most'cases it has'been proved advantageous to subject a mixture of the chlorids to electrolysis and, if the chlorids shouldhave been obtained separately, to mix them together before 'electrolyzing them. The mass from the melting-crucibles is either introduced liquid into the decomposing-furnace or, after cooling, it can be introduced in pieces and melted downtherein at a mod- It is advantageous to fill the furnace ,to about two-thirds of its capacity.

In carrying out the electrolysis a current having a tension of from 0.4: .to one volt is used. Specialattention requires to be paid during the process to the regulation of the temperature. It must be kept above the melting-point of the mixture of zinc and lead chlorids and of the zinc, (or the lead,) but below the boiling-point of the zinc chloridthat is to say, between the limits of 450 to GSO centigrade. As soon as the entire mass is melted the electric circuit is closed. The chlorin developed at the anode rises, as described, and is led oflt' by the'pipe E. It may be suitably stored in gas-holders and can be utilized in any manner desired. The metal separated at the cathode drops in spherical form from the same and rolls'down into the pocket G,

tional separation to be effected, and conse-v quently a separation of the several metals. There will be first separated silver and then lead; but as the silver only exists in small quantities and does not melt at the tempera ture of 450 to 680 centigrade the electrolysis is at the first stage of the process conducted in such manner that simultaneously with the silver a certain quantity of lead is separated, which forms with the silver an easily-fusible alloy. This alloy then drops from'the electrodes into the pocket. During this stage samples should be frequently taken and examincd as to percentage of silver. As soon as silver ceases to appear in appreciable quantitles the lead containing silver is tapped off. As a second fraction of the electrolysis pure lead is separated. After tapping this off the metal now discharged consists of an alloy of the last residues of the lead with the other metals present with the exception of zinc. The electrolyte then only consists of pure zinc chlorid, from which lastly chemically pure zinc is obtained. The zinc and lead obtained by the electrolysis are absolutely purethat is to say, of one hundred per cent.

The periods of time within which the several. metals are separated and consequently the discharge must take place are determined by an analysis of the particular product em ployed and depend upon the nature of the electrolyte.

During the process the tension of the current is made to vary. For the separation of the lead a tension of 0.4 to 0.5 of a volt is sufficient. During the separation of the zinc a tension of from 0.8 to one volt is employed.

In some cases it is desirable to regulate the electrolytic process. This is effected by means of suitable additions which influence the meltin g temperature and the conducting power of the electrolyte. As such additions I may use, among others, sodium chlorid, potassium chlorid, magnesium chlorid, calcium chlorid, sodium fluorid, fluor-spar, and the like.

Certain kinds of commercial zinc chlorid, in particular those which proceed from colormanufactories, can not be dehydrated by melting only, and contain in addition to organic substances in many cases ammonium chlorid. If such zinc chlorid is subjected to electrolysis, then at the commencement thereof there will escape oxygen chlorin hydrochloric acid, and ammonia, which cause an objectionable frothing of the melt combined with the defective separation of the metals. For preventing this disadvantage'an addition of litharge, red lead, zinc oxid, and other metallic oXids or super-oxide is employed during the melting or before the commencement of electrolysis.

The addition of the metallic oxid or superoxid in the manner set forth is for the purpose of neutralizing impurities which may be present in the electrolyte, such as ammonium clorid or free muriatic acid. Such impurities, as well as water, if present, may cause the electrolyte to foam, as they cause a secondary decomposition by Which gases-such as hydrogen, chlorin, and oXygen-are given off. These gases form bubbles which rise and cause foam. Being in a nascent state they are liable also to unite by their affinity and again mingle with the electrolyte, from which they are again evolved.

The chemical action may be stated as follows: If the electrolyte contains ammonium chlorid, the addition of oxid of lead and the resulting combinations may be stated by the equation JWILGl-kPbO:lbCh-l-IhO-l-QNIL,

If oxid of zinc is used, the formula will be:

QNIiLCl-l-ZnO ZnCh-l-ILO-l-ENIQ.

Thus the ammonium chlorid is decomposed by these oxids and combined with the electrolyte.

If organic matter is present, a superoxid of lead will destroy it. If free muriatic acid or hydrochloric-acid gas is present, by which hydrogen would be formed at the cathode, the metallic oXid will convert the muriatic or hydrochloric acid to the chlorid of the metal used. This is expressed by the following equations:

By adding chlorid of lead to an electrolyte strongly charged with chlorid of zinc and retaining water the latter will be removed by physical displacement in accordance with the natural law.

The chlorin developed of the anodes is collected in suitable gas*holders,and is led thence through vertical, horizontal, or inclined clay retorts filled with coke, charcoal, or anthracite and heated to a low red heat, steam being at the same time forced in. The apparatus for this purpose is shown in Fig. 4 and is as follows: To obtain muriatic acid from the chlorin, a retort heated from the outside and made of fireproof material can be used. That which seems to fulfill all conditions best is an upright retort heated from the outside by m cans of generator-gas,as represented in Fig. 4. The apparatus, as represented in the drawings, consists of an upright retort S, made of fireproof material, which is bricked up in such a manner that it may be heated by means of generator-gas,inducted by means of pipes into the fire-space. These retorts IIS have a movable cover 3, which by means of an appropriate locking device is fastened during the operation. The retort is filled from above with coke and is then heated to a medium redtheat. Ohlorin is then introduced by means of pipe T. At the same time steam is admitted into the retort by means of steampipes XV and w. The gaseous products originating from this combination of coke, steam, and chlorin-such as muriatic acid, oXid of carbon, and carbonic acidare led through pipe U into condensing vessels V, (the drawings show only one of these vessels,) where the muriatic acid condenses. A reaction will then take place under these conditions between the carbon, water, and chlorin according to the following formula:

IIcrc will consequently pass away from the retort together with the hydrochloric-acid gas a mixture of carbonic acid and carbonic oxid. The hydrochloric acid is condensed out of this mixture in the ordinary condensing apparatus and the chlorin absorbed by water in the ordinary manner.

By the above-described method it is rendered possible to convert any quantity of ehlorin in a very short time into absolutely pure hydrochloric acid.

The carbonic-oxid and carbonic-acid gases on issuing from the hydrochloric-acid-conden sin g apparatus are collected in gas-holders and may be utilized in any desired manner.

Having now particularly described and ascertained the nature of thisinvention and in what manner the same is to be performed, I declare that what I claim is An. apparatus for practicing the described process comprising a retort, or vessel, which is oval in cross-section, said retort being so inclined that the plane coinciding with its major axis and perpendicular to the sides of said vessel is inclined at an angle with a vertical line, anodes and cathodes sealed hermetically in said retort and havingalike inclination, the anodes being arranged over, or

above the said plane and the cathodes on the under side of and below said plane, said electrodes being formed of intersecting parts having openings between the intersections, substantially as described.

RICHARD OT"OKAR LORENZ.

\Vitnesses:

LUDWVIG KOENIG, MAX WAGNER. 

